Which of these numbers is composite? ${31,\ 37,\ 47,\ 60,\ 97}$
Answer: A composite number is a number that has more than two factors (including 1 and itself). 31, 37, 47, and 97 each have only two factors. The factors of 60 are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60. Thus, 60 is the composite number.